Electrochemical Interface Optimization toward Low Oxygen Transport Resistance in High‐Temperature Polymer Electrolyte Fuel Cells

Abstract

Due to the enhanced tolerance of CO‐containing species under elevated operation temperature around 150–220 °C, high‐temperature polymer electrolyte fuel cells (HT‐PEFCs) have drawn extensive interest in the recent decades. One of the major challenges remaining for HT‐PEFCs is the inferior cell performance ascribed to poor catalytic activity and mass transport, which are mainly determined by the electrochemical interface structure involving phosphoric acid electrolyte. Herein, the electrochemical interfaces are investigated and optimized by adjusting the hydrophilic phases within the catalyst layer (CL) to modulate phosphoric acid redistribution in the cathode. The electrochemical surface area and interfacial oxygen transport resistance in the CL are optimized by balancing the coverage of polytetrafluoroethylene (PTFE) and phosphoric acid on the catalyst surface, thus achieving an enhanced cell performance of the HT‐PEFC of up to 328.12 mW cm−2. This balancing strategy for optimizing the electrochemical interfacial structure could shed light on the development of electrode architecture design for energy conversion and storage devices.

Molecular Dynamics Study of Reaction Conditions at Active Catalyst-Ionomer Interfaces in Polymer Electrolyte Fuel Cells

“…Xiao et al found that, by decreasing the hydrophilicity of the coating polymer in high temperature fuel cells, oxygen transport resistance at the interface was reduced. 56 A similar effect is observed in the present model system; by adding more sidechains, the hydrophilicity of the ionomer skin layer increases and oxygen movement through the ionomer region is reduced. Clean graphite, being hydrophobic, allows for oxygen to approach.…”

Uneven phosphoric acid interfaces with enhanced electrochemical performance for high-temperature polymer electrolyte fuel cells

“…The single cell was assembled as described in ( 41 ). Conventional and electrospun MEAs were compressed by a ratio of 20 to 30%.…”

Challenges and opportunities for characterisation of high-temperature polymer electrolyte membrane fuel cells: a review

“…168 SEM has also been widely used for qualitatively assessing the surface of the deposited material or layers; such as catalyst layer or membranes. [493][494][495][496][497][498][499] Cross-sectional SEM is a useful technique to assess membrane and electrode thickness, pore size distribution, catalyst location, catalyst layer structure and defects. 70,103,127,161,378,380,488,489,[493][494][495][499][500][501] For HT-PEMFCs this has been shown to be useful for tracking acid loss out of the membrane via thickness changes.…”